Retractable hypodermic safety syringe

ABSTRACT

A retractable hypodermic safety syringe device is provided for encapsulating a needle after use to prevent accidental needlesticks. The retractable syringe device includes a syringe barrel having one or more locking tabs for securing a needle carrier. A hypodermic needle attached to the needle carrier. A plunger having a piston slideably mounted within the syringe body. Locking fingers on the needle carrier for receiving the plunger.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not applicable.

STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

[0003] Not applicable.

BACKGROUND OF THE INVENTION

[0004] 1. Field of the Invention

[0005] The present invention relates to a retractable hypodermic safety syringe. In particular, the present invention relates to a safety syringe for completely encapsulating a needle after use to prevent accidental needlesticks or reuse of the needle.

[0006] 2. Description of the Related Art

[0007] Healthcare workers in the United States suffer over a half million needlesticks each year. From these needlestick injuries healthcare workers contract HIV, become infected with hepatitis C and hepatitis B, and acquire such infectious diseases as tuberculosis, syphilis, malaria, herpes, diphtheria, gonorrhea, typhus and Rocky Mountain spotted fever.

[0008] Healthcare workers worldwide are concerned about accidental needlesticks resulting in life-threatening infections. Often, healthcare workers become patients after being injured by contaminated needles. These healthcare workers contract potentially deadly infections from needlestick injuries that are largely preventable.

[0009] Many methods and devices have been created to reduce accidental needlesticks by contaminated needles. An example of such a device is shown in U.S. Pat. No. 4,790,822. This patent discloses a retractable hypodermic safety syringe that retracts the used needle into the barrel of the syringe after use. A disadvantage of this design, however, was the expense and the difficulty of manufacture related to the molded internal parts of the syringe barrel, such as shoulders. Another disadvantage included the close tolerances [on what parts?] Another disadvantage of this device was the inability to evacuate the entire contents of the cavity.

BRIEF SUMMARY OF THE INVENTION

[0010] Briefly, the present invention provides an improved retractable hypodermic safety syringe that allows the needle to be retracted into the syringe cylinder after an injection has been given without the practitioner contacting the needle, thereby avoiding contamination by infectious agents. The retractable syringe device is simple and convenient to use. Additionally, the retractable syringe device is easy to manufacture because there are few internal parts molded to the inside of the syringe barrel. Moreover, the device includes locking and releasing tabs that provide a positive locking mechanism without the need for close tolerance snap fittings. Further, the retractable syringe device provides a means for evacuating the entire contents of the syringe barrel and needle carrier cavity.

[0011] The retractable syringe device includes a syringe cylinder, and a needle carrier for securing a hypodermic needle. A plunger snap coupling engages the needle carrier, allowing the needle carrier to be slid into the cylinder as the plunger is retracted to a locked position. As this snap coupling occurs, further pressure on the plunger also releases a set of positive locking tabs that secure the needle carrier to the syringe cylinder. This set of locking tabs insures that the needle carrier will not become dislodged during normal operation of loading and injecting medications.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0012] A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings, in which:

[0013]FIG. 1 is an elevational view of the retractable hypodermic safety syringe of the present invention;

[0014]FIG. 2 is a side elevational view of the device in FIG. 1;

[0015]FIG. 3 is a side elevational view, partially in section, as viewed along line 3-3 of FIG. 2;

[0016]FIG. 4 is a side elevational view, partially in section, of the device in FIG. 1;

[0017]FIG. 5 is an expanded side elevational view, partially in section, of a portion of the device within circle 5 of FIG. 4;

[0018]FIG. 6 is a side elevational view, partially in section, of the device in FIG. 1;

[0019]FIG. 7 is an expanded side elevational view, partially in section, of a portion of the device within circle 7 of FIG. 6;

[0020]FIG. 8 is a side elevational view, partially in section, of the device in FIG. 1;

[0021]FIG. 9 is a side elevational view, partially in section, as viewed along line 9-9 of FIG. 8;

[0022]FIG. 10 is an expanded side elevational view, partially in section, of a portion of the device within circle 10 of FIG. 8;

[0023]FIG. 11 is a side elevational view of the device in FIG. 1;

[0024]FIG. 12 is a side elevational view, partially in section, of the device in FIG. 11; and

[0025]FIG. 13 is an expanded side elevational view, partially in section, of a portion of the device within circle 13 of FIG. 12.

DETAILED DESCRIPTION OF THE INVENTION

[0026] A retractable hypodermic safety syringe device 30 according to the present invention is shown in FIG. 1 prior to use. The retractable syringe device 30 includes a syringe barrel or body 1 for holding injectable fluids. A plunger 14 is inserted at one end of the syringe barrel 1. The opposite end of the syringe barrel 1 includes a needle carrier 4 which receives a hypodermic needle 13 for injecting patients.

[0027] The syringe barrel 1 includes locking tabs 3 for securing the needle carrier 4 to the syringe body 1 prior to retraction of the needle 13 into the syringe body. In the preferred embodiment, the locking tabs 3 are molded into the wall of the syringe body 1. A notch 21 on the needle carrier 4 receives a lip portion 32 of the locking tabs 13 and secures the needle carrier 4 within the syringe barrel 1. The syringe barrel 1 also includes a lower body portion 23 for abutting the needle carrier 4 on a front surface 7. The combination of the locking tabs 3 and the lower body 23 works to retain the needle carrier 4 within the syringe barrel 1 during loading of the syringe and injecting of the fluid into a patient.

[0028] Referring to FIGS. 2 and 3, the retractable syringe device 30, is shown with the plunger 14 in the fully retracted position. The plunger 14 includes a piston 15 and a plunger snap 16 extending from the piston for engaging the needle carrier 4. Outward travel of the plunger 14 within the syringe barrel 1 is limited by a plunger seal interference ring 26 located on the interior of the syringe barrel 1. Typically, the syringe barrel is made from a mold which includes relief for the interference ring 26. A plunger seal 24 secured to the plunger 14 includes a plunger wiping ring 25 which contacts the interference ring 26 when the plunger 14 is extracted during loading of the syringe barrel.

[0029] The needle carrier 4 includes the notch 21 for receiving the locking tabs 3 to secure the needle carrier 4 to the syringe barrel 1. The needle carrier 4 also includes a carrier seal 5 sized to be in an interference fit with the inner wall on the syringe body 1. The carrier seal 5 prevents fluid from leaking out of the syringe barrel 1. Fingers 9 for receiving the plunger snap 16 extend from a cavity 6 of the needle carrier 4. The needle 13 includes a conical fitting 12 which is pressed and sealed onto a carrier conical fitting 8.

[0030] Referring to FIGS. 4 and 5, the plunger 14 is pushed into the syringe barrel 1 by means of a plunger grip 20 and a syringe body grip 2 until resistance is felt due to the contact of the snap 16 with the locking fingers 9. The resistance occurs when the load is ejected from the syringe and when the syringe is being loaded with fluid. Upon feeling the resistance, the user appreciates that the plunger snap 16 is almost engaged by the FIG. 9 of the needle carrier 4. At this point, the plunger piston 15 is moved into the geometrically matching cavity 6, which purges the load (or air, if in fill mode) from the cavity 6.

[0031] As shown in FIGS. 6 and 7 when the injection is finished and it is desired to set the needle 13 to the safe position (as shown in FIG. 12) the user must apply sufficient pressure to the plunger grip 20 to spring the carrier locking fingers 9 open and allow the plunger snap 16 to pass through and lock behind the carrier locking fingers 9. As shown in FIGS. 8-10, as the user continues to apply pressure to the plunger grip 20, a plunger push surface 17 contacts a rear surface 11 of the needle carrier 4 until a plunger stop 19 on the plunger 14 contacts the syringe body grip 2.

[0032] At this point, the needle carrier 4 has moved sufficiently to allow the locking tabs 3 to release from the notch 10 of the needle carrier 4. The locking tabs 3 are sprung to the position shown in FIG. 10, returning to their normal “as molded,” pre-loaded position. To insure the locking tabs 3 are ejected from the notch 10, a carrier tab ejection surface 21 on the needle carrier 4 is used to push the locking tabs 3 outward as the needle carrier 4 is pulled back by the plunger 14.

[0033] For the device to work properly, the force to slide the needle carrier 4 and release the locking tabs 3 must be greater than the snap mechanism comprised of the plunger snap 16 and the fingers 9. This insures that the locking tabs 3 do not disengage until the plunger grip 20 has had sufficient force applied to cause the snap engagement of the plunger snap 16 and fingers 9. The force required for releasing the tabs 3 is much greater than what is felt in normal filling and dispensing of the load. As a result, the locking tabs 3 will stay engaged until the user desires release of the needle carrier 4.

[0034] Referring to FIGS. 9 and 10, as the needle carrier 4 is pushed by the plunger 14, a carrier front surface 7 contacts a syringe body ramp 22 on the lower body portion 23, which causes the lower syringe body 23 to flex outward. The force required to cause the flex and allow travel of the needle carrier 4 is greater than the force required to engage the plunger snap 16 and the carrier locking fingers 9, thereby insuring the locking tabs 3 are held in place in the notch 10 until after this snap occurs. The deflection force of the lower syringe body 23, as shown in FIG. 9, is applied by the distortion strain of the circular cross section geometry, as relieved by a syringe body slot 27.

[0035] Referring to FIGS. 11-13, with locking tabs 3 disengaged, the plunger 14 can now be pulled to the fully retracted position by the plunger grip 20 until the plunger wiping ring 25 passes the plunger seal interference ring 26, indicating to the user the end of travel of the plunger 14. At this point the plunger 14 can be broken at a plunger break-off notch 18, leaving the plunger piston 15, plunger seal 24, needle carrier 4, and needle 13 inside the syringe body 1. This assembly is held in position by the plunger wiping ring 25 and the plunger seal interference ring 26. The needle 13 is recessed a distance 28 to protect the user from needlesticks. 

We claim:
 1. A retractable hypodermic safety syringe device comprising: a syringe barrel with a hollow interior and open on each end, said syringe barrel having a distal end with an inwardly protruding ramp; a locking tab attached near said distal end of said syringe barrel, said locking tab including a lip protruding into said hollow interior; a needle carrier for securing a hypodermic needle, said carrier including a notch for receiving said lip and a surface for contacting said ramp; a plunger sideably mounted within said syringe barrel; a piston secured to an end of said plunger, said piston having a snap extending therefrom; and locking fingers on said needle carrier for receiving said snap, said fingers extending away from said hollow interior of said syringe barrel.
 2. The retractable hypodermic safety syringe device according to claim 1, wherein said locking tab and said syringe barrel are molded together.
 3. The retractable hypodermic safety syringe device according to claim 1, further comprising a seal secured to said plunger for preventing fluid from leaking from said syringe barrel.
 4. The retractable hypodermic safety syringe device according to claim 1, wherein said plunger includes a notch for fracturing said plunger.
 5. A method for retracting a hypodermic needle into a syringe barrel, the method comprising the steps of: locking a needle carrier within the syringe barrel by extending a tab from said syringe barrel to a notch on said needle carrier; securing a hypodermic needle to said needle carrier; pushing a slideable plunger containing a snap within the syringe barrel so as to engage said snap with fingers on said carrier and to discharge a fluid within the syringe barrel; and retracting said plunger with said needle carrier such that said hypodermic needle is completely encapsulated by the syringe barrel.
 6. The method for retracting a hypodermic needle according to claim 5, further comprising the step of breaking said plunger at a notch on said plunger. 